Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
Deferred tax assets:
Basis difference in HLA	$ 126,219	$ 94,608
Tax Receivable Agreement	16,652	9,195
Fixed assets	26	0
Net operating loss carryforwards	1,843	1,861
Valuation allowance	(37,164)	(32,545)
State taxes	150	262
Total deferred tax assets	$ 107,726	$ 73,381